In order to improve humid aging resistance of polyester polyurethane elastomeric fibers, various attempts have been hitherto made. For example, it is known to use polylactone polyester diols or polycarbonate polyester diols, to use hydrophobic polyester diols having low ester linkage density, or to crosslink the polymer terminals of polyurethanes.
However, in the polyester polyurethane elastomeric fibers obtained by these known techniques, not only does production cost become higher, but also improvement of humid aging resistance is still insufficient. Further, elastic recovery of the fibers is often lowered. Thus, no satisfactory process for the production of polyester polyurethane elastomeric fibers having sufficiently improved humid aging resistance can be found yet in this field.
On the other hand, in the field of urethane elastomers and paint, an attempt to improve adhesion and water resistance has been made by using a silyl compound as an ingredient of a curable adhesive polyurethane (see Japanese Patent Kokai No. 57-211118). However, according to this technique, it is not possible to obtain normal fibers by spinning because crosslinkage occurs prior to spinning.
Further, it has been proposed to introduce crosslinkage into polyurethanes to improve elastic recovery and heat resistance (see Japanese Patent Kokai No. 58-163727). However, according to this technique, spinning is not possible because of gel formation prior to spinning.